The line comes from Half Baked, a 1998 stoner comedy built around friends whose marijuana use repeatedly gets them into trouble. On soundboards and in short meme edits, the phrase has been lifted out of the film and turned into shorthand for everyday forgetfulness, from lost keys to forgotten appointments. It endures because the joke is self-contained: no setup or knowledge of the movie is needed to understand it, and its calm delivery makes the irony land even harder when it follows an obvious memory lapse.